Laser Welding of wood to plastics

Kurzfassung

A German institute made investigations for applications in the field of welding of fibre-reinforced thermoplastic and wood composites with polymers. Weldability and weld behaviour of materials using different laser beam sources, new thermographic approaches for evaluation of materials qualification and investigations of different properties of plastic and wood components were made. Industry partners are sought for application of the technology or joint further application development.

Details

Laser beam transmission welding is an innovative and promising technology for many industries such as the automotive, electronic and medical industry. Due to the extension of this technology to wood components, it is also interesting for the woodworking and furniture industry.

A German institute has carried out several investigations in the field of welding of fibre-reinforced thermoplastic and wood composites with polymers. Focus is given to the determination of the weldability and weld behaviour of different thermoplastic and wooden materials in matrices relevant for recent industrial applications. At the institute, laser beam sources at different wavelengths are examined, e.g. high power diode laser (810 nm, 940 nm) and Nd:YAG (Neodymium Yttrium Aluminium Garnet) laser systems (1064 nm). New approaches using thermographic methods for an easy and fast evaluation of materials qualification regarding their weldability are also developed. Different plastic and wood components taking into account properties like filling content are investigated.

The technology is an outcome of a two-year applied research project.

Innovative Aspects:
Welding speeds up to several m/min can be reached. For evaluation of the qualification of the different materials related to their laser weldability, a thermographic system has been developed for detecting influences of glass-fibre reinforcement and material composition on transmission, absorption and scattering of the polymeric and wooden materials under investigation. Since natural fibre composites have strong material inhomogenities and anisotropic structures, special process strategies for their application have been developed.

With comparison to conventional joining techniques, laser beam welding of polymeric and wooden components provides several advantages concerning high flexibility, contact-free energy coupling (resulting in no mechanical load on the final part), invisible weld, high strength and processing in hardly accessible places. Furthermore, the good focusing properties of the laser beam and precisely controlled power density within the processing zone can be used. Moreover, contamination-free processing is possible. CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) control is also inherent.